A rock drill uses a drill string made up of drill rods and/or drill tubes, added to or taken away from the drill string, to achieve the required drilling depth for blast holes. The rock drill may use impact waves transmitted down the drill string along with rotation to the drill bit to fracture the formation being drilled into. During the drill string impact and rotation, the drill string joints may tighten and make them difficult to break loose from one other.
When the desired drilled hole depth is achieved, the drill rods and/or drill tubes are removed one at a time for storage. A typical method of breaking loose the joints between the rods or tubes is to stop drilling entirely while the drill string is at the bottom of the hole, reduce the feed pressure against the drill string, and start rattling. Rattling the drill rods and/or drill tubes is when the drill string rests against the bottom of the drilled hole and percussion impacts from the rock drill are used to impart compressive and tensile impact waves to loosen the drill string joints.
Some drill string components may be more difficult to break loose the joints than others due to a variety of reasons. Often an experienced driller can tell by the change in sound while rattling if the drill string joints have been broken loose. However, often only some of the joints are broken loose in a string, while others remain tightened, and the driller needs to use other means and/or methods to break the drill string joints loose.